1. Field of the Invention
The present invention relates to injection apparatus for softening plastics materials so that they can be injected through a manifold, into a mold, to provide a part of predetermined cross-sectional configuration. More particularly, the present invention relates to injection apparatus in which two injection units are provided, each injection unit feeding material into a single manifold for co-injection of plastics materials from two separate sources, wherein the injection units are supported in a common plane to feed a common manifold, and the longitudinal axes of the respective injection units are disposed at an acute angle relative to each other. The common manifold, in turn, feeds material into an injection mold.
2. Description of Related Prior Art
U.S. Pat. No. 5,076,777, issued Dec. 31, 1991, to W. T. Schmitt, discloses a pair of extruders for feeding a single extrusion die, configured to produce a particular cross-sectional shape. The extruders converge on the extrusion die, and the extruder axes lie in a common vertical plane.
U.S. Pat. No. 3,797,808, issued Mar. 19, 1974, to C. Y. Ma et al, discloses structure and control of an injection molding machine.
U.S. Pat. No. 4,701,292, issued Oct. 20, 1987, to E. I. Valyi, discloses a method and device for injection molding of two resins.
U.S. Pat. No. 4,657,496, issued Apr. 14, 1987, to H. Ozeki et al, discloses a hot runner mold for injection molding of two resins.
U.S. Pat. No. 4,931,234, issued Jun. 5, 1990, to R. D. Schad et al, discloses a manifold for co-injection of resins from two sources.
U.S. Pat. No. 4,808,101, issued Feb. 28, 1989, to R. D. Schad et al, discloses a manifold for tri-injection of resins from three sources.
In the course of operating extruders and injection units, it is at times necessary to remove the plastication screws, either to permit repair of the original screws, or to permit substitution of different screws. The plural units of prior art co-injection molding machines and co-extruders are not readily retracted from the common manifold.
The inventors herein have determined that it would be of great advantage in a co-injection machine to be able quickly and automatically accomplish the following:
(a) disconnection of the manifold injection nozzle from a mold element, and PA1 (b) disconnection of the injection unit nozzles from the common manifold. If these goals are accomplished, the manifold nozzle may be purged without directing purging material through the mold element and, optionally, each injector unit nozzle may be separately purged without directing purging material through the manifold. Further, the manifold may be more readily adapted to mold assemblies. PA1 (a) a machine base including a mold element support; PA1 (b) a co-injection manifold having first and second injection site means for receiving plasticated material and manifold nozzle means for discharging plasticated material; PA1 (c) a first injection unit, including a first injection nozzle; PA1 (d) a second injection unit, including a second injection nozzle; PA1 (e) means for biasing the first and second injection nozzles into respective first and second injection site means; and PA1 (f) means for simultaneously moving the co-injection manifold and the first and second injection units, in unison, with respect to the mold element support.
The inventors herein have also determined that it would be of great convenience in a co-injection machine to be able to selectively and independently move the injection units transversely of their respective longitudinal axes, for servicing the units.